function apply(tbl){
	
}
function teacher(tbl){
	var cnd=Cnd.NEW();
	if(tbl.id!=undefined){
		cnd.and("id","=",tbl.id)
	}else if(tbl.name!=undefined){
		cnd.and("name","=",tbl.name)
	}
	var teacher=$fetch("teacher",cnd);
	teacher.put("courses",$list("course",Cnd.where("teacher","=",teacher.name).desc("id")))
	var comments=$list("comment",Cnd.where("tbl_name","=","teacher").and("tbl_id","=",teacher.id))
	attr("comments",comments)
	return teacher;
}